The Trump administration is suddenly warning would-be foes and touting its leader as a no-nonsense commander in chief, after focusing mostly on domestic policy for its first 77 days.

Last week, the White House was still very much concentrated on health care, a tax overhaul and other domestic agenda items. It held special advance briefings on Trump’s summit with his Chinese counterpart, addressing trade and his use of the Congressional Review Act. It centered on U.S. jobs and on rolling back Obama-era regulations to give a boost — as the administration contends — to the American economy. Trump’s aides were very much in a mode to enact his “America First” agenda, pushing his efforts to “rebuild our country,” as the president himself often puts it.

Then, with a single order on Thursday evening, the White House was transformed.

The inward-focused administration with the isolationist president had broken with key allies by signaling that Syrian President Bashar Assad did not necessarily have to relinquish power. But over 72 hours, after Trump viewed images of babies killed by what the U.S. said was an Assad-ordered gas attack in Syria, the domestic-focused White House began flexing its muscles. It launched a salvo of Tomahawk missiles at a Syrian airbase.

“When you watch babies and children being gassed and suffer under barrel bombs, you are instantaneously moved to action,” Trump’s chief spokesman said. “I think this president has made it very clear that if those actions were to continue, further action will definitely be considered by the United States.”

Spicer reiterated the president’s pledge to avoid telegraphing any U.S. military actions he orders during his tenure, but he concluded that statement with a hawkish warning to enemies and would-be foes: “But make no mistake, he will act.”

“Talking tough, be it on domestic matters or on foreign policy, only succeeds if you have results to show from it,” said Christine Wormuth, a former Pentagon policy chief, now at the nonpartisan Center for Strategic and International Studies.

“If you talk tough and fail to back it up, the credibility of the United States is diminished,” Worthmuth said. “If you act and things don’t go well, it can have tremendous consequences.”

Senior aides say Trump is prepared, if provoked, to act militarily again in Syria. They are also talking tough with a message for other would-be foes such as Iran, Russia and North Korea: If you test this new president, he is prepared to strike.

“So what the president chooses to do — I hope that what Iran sees, and Syria sees, and Russia sees is that this is a president that’s not afraid to act,” said Nikki Haley, the U.S. ambassador to the United Nations.

“But I don’t think anything is off the table at this point,” Haley said in an interview on CNN’s “State of the Union” that aired Sunday. “I think what you’re going to see is strong leadership. You’re going to continue to see the United States act when we need to act.”

Her comments came the same day the Trump administration ordered a U.S. Navy carrier strike group to head to the Pacific region to provide a check on potential North Korean aggression.

To that end, Secretary of State Rex Tillerson had a message for the North’s defiant leader, Kim Jong Un.

“I think the message that any nation can take is if you violate international norms, if you violate international agreements, if you fail to live up to commitments, if you become a threat to others, at some point a response is likely to be undertaken,” Tillerson said Sunday. “And I think in terms of North Korea, we have been very clear that our objective is a denuclearized Korean peninsula.”

The new chief U.S. diplomat denied reports that the Trump administration is mulling a way to remove the country’s youthful leader from power. But 24 hours later, an administration ally in Congress said that could be on the table.

“I think there is a question of who would follow him, and in the conversations I’ve had with experts on North Korea, I don’t think anybody has that answer,” Colorado Republican Sen. Cory Gardner said Monday on MSNBC’s “Morning Joe.”

The Senate Foreign Relations member called on the Trump administration to work with allies in the region and China to “develop a plan not only for denuclearization of Kim Jong Un’s regime, but what happens next” because “it’s a very important question that we do not have answered at this point.”

The president hinted last week he wants to stick to his “America First” belief system and campaign promises, but will be “flexible” and act militarily should circumstances around the globe dictate it. But experts and lawmakers are befuddled by just what principle is guiding Trump’s foreign policy.

“If anybody thinks they know the defense strategy of the president of the United States,” Senate Minority Whip Richard J. Durbin of Illinois said Friday after a closed-door briefing with administration officials about the decision to strike Syria. “I wish they’d sit me down and share it with me.”

Asked to define the “Trump doctrine” of managing the country’s foreign affairs, Spicer was firm on Monday that it remains “America First.” He further explained that Trump feels there must be a “clear and defined” U.S. interest at stake before he acts, saying his boss will not be the “world’s policeman.”

But Wormuth, who was undersecretary of Defense for policy from 2014 until 2016 under President Barack Obama, said, so far, she “can’t discern what his worldview is.”

Wormuth also questioned Spicer’s “America First” description.

“Well, OK, to me that’s more of a campaign speech,” she said. “I don’t see what broader strategic thoughts or objectives are guiding the president at this point — nor how to achieve them.”